The U.S. Department of Transportation said Thursday that an investigation also determined that Coach USA Tour Inc. drivers falsified paperwork and that the company didn't keep proper records.

The DOT's Federal Motor Carrier Safety Administration ordered it to cease operations as of Wednesday.

Coach USA Tour Inc. President Lucy Shun says by phone that she disagrees with some of the findings, including that the six-bus fleet wasn't properly maintained. But she says the company will work with the DOT to address the issues with the hope of resuming operations as quickly as possible.